Bobby Hatfield, who, along with Bill Medley, comprised the classic 1960s duo The Righteous Brothers, died Wednesday in a hotel room in Kalamazoo, Mich., where he was found half an hour before the duo was to perform a concert at Western Michigan University’s Miller Auditorium. An autopsy was to be performed, according to the Kalamazoo Gazette, to determine the 63-year-old’s cause of death.

The Righteous Brothers were known for their ”blue-eyed soul” sound, which combined Hatfield’s gritty voice, Medley’s deep baritone, and lushly arranged ballads. They scored such mid-’60s hits as “You’ve Lost That Lovin’ Feeling” (which the duo claimed was the most-played song in radio history), ”Soul and Inspiration,” and ”Unchained Melody,” whose re-recorded version for the 1990 film ”Ghost” earned Hatfield and Medley a Grammy nomination. Earlier this year, the pair were inducted into the Rock and Roll Hall of Fame.